Those were the days when seikomatic-p was only available for Japan domestic market only and therefore, marked "-p" and the case back number usually started with 5106 - xxxx ; xxxx could be 7000 or 8010 or 7040 or 7050 ;

When engraved with "presmatic", it was for export，serial no started with 5146 - xxxx ; xxxx could be 7000 and others..